Re: [PATCH] maint.mk: don't maintain a second build-aux variable.

[Jim Meyering]

Gary V. Vaughan wrote:
> I was wondering why 'make stable' would always use a stale version unless
> I manually updated my .version file first.  It turns out that if you use
> a non-standard build-aux location, you have to tell GNUmakefile by setting
> _build-aux to get the .version dist-hook machinery, and that you also have
> to set build_aux in order for maint.mk to work properly.
>
> Before this patch, my cfg.mk needed:
>
>   build_aux = $(srcdir)/libltdl/build-aux
>   _build-aux = libltdl/build-aux

I would leave them for now, but factor out the duplication:

    _build-aux = libltdl/build-aux
    build_aux = $(srcdir)/$(_build-aux)

> This patch combines the two so that you I declare my build-aux directory
> with just:
>
>   _build-aux = libltdl/build-aux
>
> Alternatively, we could change maint.mk to read:
>
>   build-aux = $(srcdir)/$(_build-aux)
>
> ...but that leaves open the possibility of users like me only setting one
> or the other variable in cfg.mk and wondering why things almost work, but
> not quite.  I think this is the cleaner, safer solution.

Wouldn't that break things for those who customize build_aux?
How about merely ensuring that they're consistent, for now,
i.e., by adding something like this:

ifneq ($(build_aux),$(_build-aux))
  $(error ...)
endif